Various internal tubal passages of a patient are subject to being totally or partially occluded by a stenosis. Examples of internal tubal passages which are subject to occlusion or partial occlusion are arteries, fallopian tubes, the cervical canal, biliary duct, pancreatic duct, ureter, urethra, eustachian tube and lactiferous ducts. When occlusion or partial occlusion of an internal tubal passage occurs, it is typically necessary or desirable to remove or partially remove the stenosis to recanalize the tubal passage.
There are a variety of known techniques to achieve tubal recanalization and these includes, for example, Dottering techniques using wires, hydro-irrigation using pressurized fluid sources and coaxial balloon catheters of the type used in balloon angioplasty. An everting catheter can also be designed as a dilatation catheter and in this event, an everting element of the everting catheter is expanded against the stenosis to reduce the stenosis. A catheter of this type is shown and described in Fogarty et al U.S. Pat. No. 4,271,839.
One problem with tubal recanalization procedures is that, so far as we are aware, there are no direct techniques to evaluate the site of the stenosis during and following the recanalization procedure. Indirect evaluations as to the severity of the stenosis can be ascertained from the magnitude of force required to cross and dilate the stenosis. Also, information can be obtained before, during and after the procedure from contrast dye injections. However, none of these procedures provide all of the information desired. In addition the use of contrast dye injections requires exposing the effected region of the patient to X-rays and this is undesirable in certain locations of the body such as the sensitive reproduction tracts of females and males.
Certain endoscopic evaluation techniques are also known. One such technique includes utilizing a balloon to position an angioscope within a central lumen of a catheter. The balloon, however, occludes the blood vessel and obscures the imaging field. Angioscopy used during balloon angioplasty provides both pre and post operative analysis. Thus, angioscopy affords the advantage of direct viewing, but is subject to a somewhat obscure imaging field and blockage of the artery.
It is also known to use an everting catheter to deliver an endoscope to an internal region of a patient such as into the fallopian tubes to visually evaluate such region. However, so far as we are aware this has not been done with an everting catheter which can also treat the stenosis.